Though the largely childhood disease is present in 10 states as close as New York and New Jersey, high vaccination rates in Berks County and Pennsylvania are helping keep measles at bay so far.

The highest measles infection rates occur in winter and spring.

The first symptoms of a classic measles case are a rash and fever. A patient can be infected and able to spread the disease four days before showing any symptoms, according to the Centers for Disease Control and Prevention.

Unlike the dreaded Ebola virus, which requires personal contact with skin, blood or other body fluids, measles is airborne. It can be spread in droplets of a sneeze. Worse yet, those droplets remain infectious on surfaces for hours until another person contacts them, said Dr. Linda Bloom, medical director of the Pediatric Hospitalist Program at Reading Hospital.

If that person is vaccinated, the chance of them contracting measles is less than 10 percent.

Although no measles cases have been reported here, parents should not let their guard down. The Centers for Disease Control and Prevention holds that about 97 percent of people who are vaccinated are protected from such incidental contact with the virus.

Measles has been diagnosed in 17 children in the Orthodox Jewish community in Brooklyn. The outbreak has been traced to travel to and from Israel, where 1,334 cases were reported as of Sunday.

Two counties in Washington and one in Oregon, where the population of unvaccinated children was as high as 40 percent, also are experiencing outbreaks. Outbreaks also have been reported in California, Colorado, Connecticut, Georgia, Illinois, New Jersey and Texas, the CDC reports.

Bloom said research has led to better vaccines. She said measles was eradicated in the U.S. in 2000. Since then, Americans got cocky. Communities that don't vaccinate became infected and measles roared back to life, Bloom said.

“People got lazy,” Bloom said. “We should be ashamed.”

Overall, the CDC says 92 percent of Pennsylvania children get the measles, mumps and rubella vaccine. That puts most of the state in what epidemiologists call community immunity, or herd immunity.

If a sufficient proportion of a population is immune to an infectious disease through vaccination it, makes the spread less likely, said Dr. Jerry Lee, a pediatrician at Penn State Health St. Joseph hospital.

“Because measles is so infectious, if you introduce it to a room of unvaccinated people, it can jump from person to person,” Lee said.

If 90 percent or more of the people in the room are vaccinated, it will stop the spread, Lee said.

The measles vaccine was introduced in the U.S. in 1963. Research led to a better version in 1968. The vaccine was so popular then that more than 95 percent of children got the MMR vaccine.

“Unfortunately, we've been a victim of our own success,” Lee said.

The downside of seeing fewer measles cases, Bloom and Lee said, can be reduced vigilance.